Re: [FFmpeg-devel] [PATCH 1/7] avcodec/h263dec: Remove redundant code to set cur_pic_ptr

[Michael Niedermayer <michael@niedermayer.cc>]

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On Mon, Aug 15, 2022 at 01:49:24PM +0200, Andreas Rheinhardt wrote:
> It is done later in ff_mpv_frame_start() (and nobody uses
> current_picture_ptr between setting it in ff_mpv_frame_start()).
> 
> (The reason the vsynth*-h263-obmc code changes is because
> the call to ff_find_unused_picture() now happens after the older
> pictures have been unreferenced in ff_mpv_frame_start(),
> so that their slots in the picture array can be immediately
> reused; the obmc code is somehow buggy and changes its output
> depending on the earlier contents of the motion_val buffer.)
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---

> I'd like to take this opportunity to once again ask anyone familiar
> with H.263 to take a look at this OBMC issue.

Iam too busy ATM :( i might look at some point but its not very high
on my todo as it works :) security & release is more important

but i can say this breaks fate as it is:

--- ./tests/ref/vsynth/vsynth1-h263-obmc	2022-08-16 00:19:00.345967181 +0200
+++ tests/data/fate/vsynth1-h263-obmc	2022-08-16 00:19:05.262017999 +0200
@@ -1,4 +1,4 @@
 7dec64380f375e5118b66f3baaaa1e24 *tests/data/fate/vsynth1-h263-obmc.avi
 657320 tests/data/fate/vsynth1-h263-obmc.avi
-f5048b5f0c98833a1d11f8034fb1827f *tests/data/fate/vsynth1-h263-obmc.out.rawvideo
-stddev:    8.12 PSNR: 29.93 MAXDIFF:  113 bytes:  7603200/  7603200
+2a69f6b37378aa34418dfd04ec98c1c8 *tests/data/fate/vsynth1-h263-obmc.out.rawvideo
+stddev:    8.38 PSNR: 29.66 MAXDIFF:  116 bytes:  7603200/  7603200
Test vsynth1-h263-obmc failed. Look at tests/data/fate/vsynth1-h263-obmc.err for details.
tests/Makefile:304: recipe for target 'fate-vsynth1-h263-obmc' failed
make: *** [fate-vsynth1-h263-obmc] Error 1

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Does the universe only have a finite lifespan? No, its going to go on
forever, its just that you wont like living in it. -- Hiranya Peiri

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